Lasagna Gardening, the Sequel – More Layers than Ever!

As fall slips away and winter rolls in, I’ve started preparing my garden for next spring. Despite my skepticism last spring (and even moreso, Chris’s) I have become a full-on believer in “lasagna gardening,” also known as “layer mulching.” This is a process wherein a gardener lays down cardboard or another semi-impermeable layer to keep out weeds, then piles several very thick layers of organic matter on top of it.

Last fall, after recycling a number of moving boxes, I put down compost from my composter, one bale of straw, a few bags of “LeafGro” (yard waste composted by the county, then resold), several newspapers, and a bunch of leaves from our yard. I waited all winter for them to break down, then in the spring claimed that “Layers of organic matter do not just magically transform into soil over the winter.” As I found out, the basis for my disappointment was fundamentally wrong. There was magic to be found – I just had the timing of the trick wrong.

Rather than the spring, when I lifted up the tarp, the real astonishment came in the summer, as I harvested pounds of potatoes, tomatoes, zucchini, and many other vegetables. Now anyone could produce that with the right chemicals. But being able to do it with almost no weeding and no chemical inputs, as I did? I’d think it was an illusion myself if the produce wasn’t filling my fridge.

Last spring, I was confused because I thought the leaves were supposed to become soil over the winter, even though I knew the freezing temperatures wouldn’t enable the necessary breakdown in organic matter. After all, how could the plants make use of the nutrients tied up in the leaves if they weren’t broken down by the time I planted the seeds?

Over time, I realized the plants were willing accomplices in my magic trick. As they grew, their roots and stems broke through the leaves, speeding up their physical decay. In addition, their roots also accelerated the chemical process, along with the work of fungus, bacteria, earthworms, and many other friendly garden critters. The more the organic matter broke down naturally, the more soil developed, the more beneficial organisms it attracted, and around and around the process went, with the plants growing stronger all the while. The entire time, the top layer of leaves didn’t decay, protecting the entire system from weed seeds looking to take advantage of a freshly disturbed area. Although it took significant front-end work last fall, it was hugely worth it for the minimal time and effort I had to expend throughout the spring, summer, and fall. The process mimics what happens in the forest to develop soil, but if that process and its results don’t seem a little magical to you, you haven’t spent nearly enough time in the woods.

Despite the success, we’re taking a slightly different tack this year, having learned a few lessons.

First, we now have a fence up around the garden, a key featured we lacked last year. Beyond its summer purpose to protect our produce from wandering deer, it has a major advantage for lasagna gardening – not having to spread a conglomeration of tarps over the space. For one, the fence makes clear that our piles of stuff are preparations for a garden and not just a “messy nuisance,” as the community police claimed it was last winter. In addition, it blocks the wind, so that the leaves are far more likely to stay on the garden rather than be blown around entire yard. Not having to deal with the tarp and its tendency to become a sail makes life much easier this time around.

Chris laying down cardboard along the pathway

Second, we’re using a lot less cardboard. The several layers of cardboard we used the first time were terrific for keeping rogue weeds from pushing through, but it also restricted our plants’ root depth. This manifested itself in a number of annoying but not fatal problems. Both our pepper plants never rooted deeply and despite us staking them, had a tendency to fall over and unroot themselves. Our zucchini plant had it even worse – along with the fact that its roots never went very deep, the tomatoes kept trying to run their roots under it! But the most surprising result were our carrots. As the root is the carrot itself, we ended up with multi-tentacled orange objects resembling a H.C. Lovecraft monster. Although the fanciful notion that perhaps Cthulhu itself had a hand in them, it’s more likely that they bumped up against the cardboard and then tried to grow around it. So this year, we’re only putting cardboard down on our pathway, not the planting beds themselves. The beds had very few weeds at the end of the season so it shouldn’t pose a problem.

Third, we tried to distribute the leaves in a different manner. Last year, I just raked up a bunch of leaves and dumped them on top of the other layers. However, because the leaves broke down very little by the spring, they were quite difficult to plant seeds into. Similarly, although most of the blame for my seedlings failing lies in my lack of hardening-off, planting them into whole leaves with little to hold onto besides planting soil didn’t help much. To avoid these problems, Chris suggested pre-breaking down some leaves before putting them on the garden. By collecting leaves with the mower, we thought we’d minimize our wheelbarrow transportation as well. Unfortunately, it totally backfired. As the mower wouldn’t suck up most of the leaves without also getting a lot of grass, the actual amount of leaves collected was miniscule. Left with no other choice, I trucked the wheelbarrow back and forth from the cemetery at least 12 times.

So the “lasagna” recipe for this year’s garden is:
– Weed the entire garden – interestingly, the very large majority of the weeds were on the path down the middle, the most disturbed part of the garden with the fewest plants posing any competition
– Layer cardboard down the walking path, then cover with mulch
– Layer newspaper on the growing beds
– Put a thin layer of LeafGro on top of the newspaper (about 2 bags)
– Put down about 4-5 inches of leaves raked as a public service to graveyard next store to our house (or you can offer to rake leaves for your neighbor with both people benefiting, especially come summer-time!)
– Layer another layer of newspapers
– Frantically spread compost to prevent the newspapers from blowing away
– Wet the entire thing with the hose to minimize the newspapers blowing away
– Top with 5-6 more inches of leaves
– Top with two more bags of LeafGro (haven’t done this yet)

Then we’ll let the whole concoction “bake” all winter and be ready to use bright and early next year. In the meantime, I’ll make real lasagna from tomato sauce in the freezer, dreaming of the summer to come.

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Nice blog :) Just wanted to mention that your leaves might not be breaking down due to a brown/green imbalance in your layers. If the leaves are dead (brown in colour and in compost ingredient terms) and ‘leaf grow’ is a completed compost, your balance is probably too brown (carbon-rich). If so, a layer or two of green (cut grass, manure, etc.) would help to keep the pile active. If the leaves are green and leaf grow is something else, the balance might be too green and you may need more brown (straw, shredded paper, etc.). Compost isn’t strongly green or brown, as it has been composted already, although I think it is slightly green, having some residual matter containing nitrogen.
Hope this helps. Just learning about all this myself :)